The invention relates to a redox battery, specifically including a bromine positive electrode and a chromium negative electrode.
Conceptually, redox batteries are attractive for utility bulk energy storage because there are no morphology changes in the electrodes. However, none of the known redox couples combine all of the properties desirable for bulk energy storage.
A number of halogen-type cells have been suggested. One such cell is a zinc-bromine battery, as described in U.S. Pat. No. 4,162,351. This is a so-called hybrid form of battery because the zinc half-cell involves plating, while the bromine half-cell is a redox type (i.e., totally soluble). In the described system, the amount of bromine in the electrolyte on the bromine side is maintained at a minimum by using a complexing agent for bromine. As described therein, a preferred form of complexing agent is a tetraalkylammonium salt, referred to as a bromine oil. One disadvantage of this type of cell is that the zinc half-cell includes the inherent problems of plating.